Nevertheless, it is soon clear from these posts that prepositions have a sizeable number of interesting similarities between them, which we might call general preposition characteristics. Here I wish to highlight seven of the more important of these characteristics, in the belief that their appreciation might help some grammar errors to be avoided.

.

LIST OF GENERAL PREPOSITION CHARACTERISTICS

1. Need for a Noun-like Partner

Prepositions are like adjectives: they usually have a noun-like partner – whether a lone noun, a noun “described” by other words, or a noun substitute. One way to distinguish prepositions from adjectives is by their position relative to a partner noun with the: prepositions go before both words (across the Nile), adjectives go in between (the Blue Nile).

Prepositions can sometimes come after their noun-like partner instead of before, for example when there is an informal use of who/which/that, like this:

Sometimes it may seem that a preposition has no partner word at all – for example in some “two-word” verbs like drop out and in a special use after BE (the time is up). However, these are not prepositional uses, but adverbial ones (see 139. Phrasal Verbs and 154. Lone Prepositions after BE).

.

2. Creation of Adjective or Adverb Phrases

A preposition and its noun-like partner together act like either an adjective or an adverb. In the adjective-like use, there must be another noun nearby, usually in front, whose meaning the phrase is expanding, like travel in this sentence:

(c) ACCORDING TO PLATO, the soul belongs to an ideal world of perfect forms.

The ability of preposition phrases to be used in these two different ways sometimes creates alternative possible interpretations. A common one is when the phrase comes between a noun and the end of the sentence (see 124. Structures with a Double Meaning). In the following example, who had the stick?

(d) The robbers hit the old man WITH A STICK.

If with a stick is adjectival, its noun is the old man, meaning that he had the stick. However, if with a stick is adverbial (saying something about the verb hit), the stick must have belonged to the robbers. Readers normally decide whether a use is adjectival or adverbial on the basis of which makes the best sense according to the surrounding sentences or their knowledge of the world. Sometimes this needs careful thought, though: the post 3. Multi-Use Words mentions a sentence with from that one learner reported as confusing.
.

3. Ability to be Multi-Word

Sentence (c) has the two-word preposition according to. Prepositions of two, three or even four words are quite common. In all cases, however, the last word will be a familiar shorter preposition like to. Other examples of multi-word prepositions are in terms of, on the basis of, depending on, in relation to, because of, courtesy of, on account of, due to, thanks to, on (the) top of, in addition to, apart from, instead of, prior to, subsequent to, by means of and in front of.

Also noteworthy is the existence of a few “compound” prepositions (formed by joining separate words into one – see 26. One Word or Two?), for example, throughout, without, upon and into.
.

4. Similarity to Conjunctions

Prepositions are easily confused with conjunctions. This is because they can often express the same kind of meaning – they differ more in their grammar than their meaning. Compare:

(e) (PREPOSITION) Car use grew during the 20th century.

(f) (CONJUNCTION) Car use grew as the 20th century progressed.

The key difference here is the verb progressed in (f). It is needed mainly because conjunctions, like as, nearly always need a following verb that is not the only verb in the sentence (the other verb here is grew). Conjunctions are considered at length in the post 25. Conjunction Positioning. If the conjunction is changed to the similar-meaning preposition during, no verb is possible.

The similarity between prepositions and conjunctions is reflected in the fact that some prepositions and related conjunctions have the same spelling. The main ones are after, as, before, since and until:

(g) (PREPOSITION) Uganda was ruled by Britain until its independence in the 1960s.

(h) (CONJUNCTION) Uganda was ruled by Britain until it achieved independence in the 1960s.
.

The first two here are easily corrected by removing the preposition. An alternative correction in (j) is to add a new noun or pronoun that can serve as the subject, such as the weather or it. Addition is also the way to correct (k) – e.g. living – though here it can only be before the preposition phrase.

Object nouns are usually bound by the same preposition rule, but an important exception occurs when the preposition is part of a two-word “prepositional” verb like DEPEND ON (see next section). Slightly different are “indirect” objects, which can be used either with or without a preposition (see 126. Verbs with an Indirect Object).

.

6. Ability to Form Prepositional Verbs

Prepositional verbs comprise a verb and a preposition, with or without a noun in between. The preposition is considered to be part of the verb rather than the beginning of a subsequent preposition phrase. Compare:

Another vocabulary-like use is in places that allow various alternative preposition meanings. This often happens, for example, when a preposition expresses a basic meaning of place, direction or time – as in tothe south(see 151. Ways of Using Compass Words), where in, into, near, from, etc. are also possible, andonFriday, which also allows by, before, after,etc. Resembling these are prepositions of a more metaphorical kind, such as behind meaning “causing” and under meaning “ruled by” (see 7. Metaphorical Meanings).